High Definition Fiber Tracking

There are numerous brain imaging techniques that allow us to gain insight into what damage the brain may have incurred after a patient has a traumatic injury. The ever popular fMRI measures blood flow to infer neural activity. Diffusion tensor imaging (DTI) uses the magnetic properties of water to look at white matter in the brain, while positron emission tomography (PET) uses radiolabeling to look for a specific chemical in the brain. All of these are important for possible disease diagnosis, however, there is skepticism around how dependent we should be on this technology, as the results should never be taken as the absolute truth.

Comparison of X-Ray to HDFT

Now, a new type of brain imaging developed by researchers at the University of Pittsburgh allows researchers to look for connections that have been broken as a result of traumatic brain injury, much like an X-Ray allows doctors to look for broken bones. It is called High Definition Fiber Tracking (HDFT). Although the technology is not specific at the cellular level, it is accurate in observing specific connections that have been lost as a result of injury. These lost connections act as a reliable predictor for cellular information, such as the percentage of axons that have been lost.

The accompanying publication in the Journal of Neurosurgery focuses on a case study of a man who sustained severe brain damage after crashing an all-terrain vehicle (public service announcement: this is why we wear helments!!!). Initial MRI scans showed hemorrhaging in the right basal ganglia, which was confirmed by a later DTI. The patient had extreme difficulty moving the left side of his body, and it was assumed to be a result of damage to the basal ganglia. It was not until the patient had a HDFT test that doctors could pinpoint the true problem: fiber tracts innervating the motor cortex had been lost.

Above is a comparison of the techniques that the researchers saw. The first column consists of scans from a normal patient, while the second two columns are the brain injury patient 4 and 10 months post injury. The imaging techniques used are MRI, DTI, and HDFT. The HDFT gives a clearer picture of what specific connections in the brain have been lost.

The following image comparing DTI with HDFT also shows the inaccuracies of the older technologies.

In healthy subjects, the DTI shows connections and fiber tracks which do not correspond with what we know about brain anatomy, including false turns (deviations from the pathway), false continuations (midline crossing), and looping (travel in random directions). The HDFT scan is consistent with brain anatomy. Thus, the use of HDFT was essential in pinpointing exactly what connections had been lost as a result of the patient’s traumatic brain injury (see Figs 5 and 6 in accompanying paper, linked below).

HDFT has the potential to become the future of diagnoses in patients who have sustained traumatic brain injury, thus revolutionizing how we can treat these patients.

The following video shows a summary of the new technology in addition to the patient in the research paper’s case study: